Serfas Vistoso 135mm wide and Forte Pro SL ~140mm wide if memory serves are great saddles. The Forte Pro is almost identical in shape to the Vistoso but it has the cutout. I've done 2 centuries on the Vistoso. Both are less than $50.

Loaner program is the way to go if you've got the LBS. If not the above are good starting points and won't break the bank.